In fact the point is to create a new wallet on a secure system, then shutdown the bitcoin client, make an encrypted backup of the wallet.dat file and delete the whole thing again (the live OS, I mean)
Then regulary move funds from your 'normal' wallet to the secure one (make a payment to one of those addresses). The balance of a wallet is kept on the network, and it is not needed to keep the savings account "live".
i think this is probably the best solution and also the beauty of bitcoin. going this route, a user could leave their savings account wallet offline for X number of years. the only reason ever to load the wallet would be to make withdrawls. actually, combine this with jrwr's
offline paper storage and you have a pretty secure system. it might be a lot of hoops to jump through, but it would be difficult to crack.